On Fri, Apr 24, 2009 at 02:14:43PM -0400, Donald Williams wrote:
> Have you tried increasing the disk readahead value?
> #blockdev --setra X /dev/<multipath device>
>  The default is 256.    Use --getra to see current setting.
>  Setting it too high will probably hurt your database performance.  Since
> databases tend to be random, not sequential.

I would think that the databases would open the disks with O_DIRECT
bypassing the block cache (And hence the disk readahead value isn't used
at all).

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